Underwater propulsion device



Aug. 7, 1962 E. R. DAVIS, SR

UNDERWATER PROPULSION DEVICE Filed June 22, 1960 FIG. 5

R .S m 3 MW A MD w. R E N E G U E BY mum JENNEY, WITTER & mumsm FIG. 4

ATTORNEYS United States Patent Ofiiice 3,048,140 Patented Aug. 7, 19623,048,140 UNDERWATER PROPULSION DEVICE Eugene R. Davis, Sn, Jay, N.Y.,assignor t Newell N. Davis, Marblehead, Mass. Filed June 22, 1960, Ser.No. 37,923 Claims. (Cl. 115-61) physical efforts. Although certainunderwater propelling means are presently available, they have notproven entirely satisfactory for one reason or another. Battery operatedunderwater vehicles, for instance, are heavy and relatively expensive tobuild and depend upon rotation of a conventional propeller which mayprove dangerous to the diver. Various other contrivances have beenproposed from time to time but, because of mechanical complexities inefiiciency or other reasons, have not met with wide acceptance.

It is an object of the present invention to provide a portable andcompact underwater fluid operated engine that is adapted to attach toand propel a diver safely through the water.

Another object of this invention is to provide a lightweight andinexpensive underwater propelling machine having no major moving parts.

Yet, another object of this invention is to provide an extremely simpleunderwater engine which may use as a source of energy either compressedair from conventional underwater breathing equipment or the divers ownexhaust.

More particularly, this engine features an underwater ram jet engineadapted to be strapped or otherwise mounted on the back of a skin diver.The engine, if

given an initial forward thrust, is operated by injecting gas underpressure into the engine duct at a point where the static pressure ofthe water flowing through the duct is greatest. The injection gas may besupplied by a tank of compressed air forming part of the diversunderwater breathing apparatus. This source may be supplemented by thedivers own exhaust if desired.

These and other features of the invention together with further objectsand advantages thereof will become apparent from the following detaileddescription with reference being made to the accompanying drawings inwhich:

FIG. 1 is a view in side elevation, partly in section of a swimmerfitted with an underwater ra-m jet engine made according to thisinvention,

FIG. 2 is a sectional view in side elevation of the engine duct shown inFIG. 1 but on an enlarged scale,

FIG. 3 is a cross-sectional view taken along the line 3-3 of FIG. 2,

FIG. 4 is .a cross-sectional view of an engine duct having a modifiedcontour, and

FIG. 5 is a modification of the engine in which an underwater ram jetengine is used to drive an underwater sled.

Referring now to FIGS. 1 and 2, the reference character generallyindicates an underwater ram jet engine comprising a duct 12 having anaxial fluid passageway 14 formed therein. The duct preferably should befabricated from a lightweight and noncorrosive material such as plasticor aluminum in the form of a pair of oppositely directed, truncatedhollow cones joined at their bases. A gas injection station is locatedapproximately mid-way along the duct where the passageway is widest.This station includes a compressed air injection nozzle and an outlet 22for introducing the divers exhaust into the fluid passageway. v p

The engine, as shown in FIG. 1, is mounted on the back of a diver inconnection with a conventional underwater breathingoutfit or anaqualung. The assembly shown includes one or more cylinders 24 ofcompressed air suitably fastened to the diver by meansof a harness 26. Apair of braces 28 engaging the cylinders 24 serve to support the engine10 rigidly thereto. When properly mounted, the engine will be arrangedwith its inlet port 16 positioned forwardly or near the divers head withI an exhaust port 13 located to the rear so that the engine will begenerally parallel with respect to the divers length and serve to propelthe diver in a head-first manner. A short section of pipe 30 extendsfrom the cylinder and is provided with a branch conduit 32 leading tothe injection nozzle 2i) through a pressure regulating valve 34-. Forease of control, the valve 34 may be provided with a remote controlarrangement comprising a flexible extension stem 36 having an adjustmenthandle 38 attached to the fixed buckle on the divers harness. Anotherpressure regulating valve 40 is connected to the pipe 30 beyond theconduit 32 and controls the flow of air through a flexible tubing 42 tothe divers mouth piece. Another flexible tubing 44 also connected to themouth piece extends rearwardly to the outlet 22 and directs the .diversexhaled air into the fluid passageway 14.

Once submerged in the water with the engine and associated equipmentattached, the diver may start the engine by giving it an initial forwardvelocity. This may be done by swimming, towing or any other suitablemeans. With water flowing through the duct, the valve 34 may be openedto inject pressurized air into the fluid passageway. high but, once theengine is operating normally and under its own power, the air may bethrottled down to whatever speed is desired. It is, of course, necessarythat the injection pressure at all times be at least slightly higherthan the static pressure of the water.

The water entering the duct through the inlet port has a portion of itsvelocity energy converted into static pressure or ram as it flows to thegas injection section of the duct. Gas is injected as desired into thewater within the fluid passageway at a point where the static pressureof the water is at a maximum. The water within the duct then has thismaximum static pressure converted back into velocity energy as ittravels to the gas injection section to the exhaust port. The gas, whichis introduced into the water stream at the highest static water pressuresection of the duct, is carried in the form of dispersed bubbles andwater foam with the water stream to the exhaust port. A combination ofwater, gas bubbles, and foam is consequently ejected from the exhaustport. The gas bubbles introduced at the point of high static pressureexpand as they are carried by the water stream toward the exhaust portdue to the decrease in static water pressure as the water pressure isconverted into velocity energy. The effective exhaust port area is thusreduced, effectively increasing the velocity energy of the water as itemerges from the duct outlet relative to the velocity energy of the ductintake.

The power output of the engine is controllable in accordance with therelationship established between the duct configuration, the watervelocity entering the duct, the quantity and pressure of gas injectedinto the duct, the static water pressure in and around the duct, the

Initially the injection pressure should be rather.

temperature of the gas, and the velocity of the duct relative to thewater.

Normally, the engine duct is circular in cross section as shown in FIG.3 but, for some installations, it may be desirable for the duct to becrescent shaped in cross section as suggested by FIG. 4. Otherconfigurations may be employed to facilitate packaging or attaching theengine to the divers air tank. The design of the ducts for non-circularcross sections will be such that essentially the same conversion ofwater velocity energy to static pressure and the reconversion of staticpressure back into water velocity energy will be maintained as whenusing the duct circular cross section.

In FIG. 5, there is shown a modification of the engine. In thisembodiment, an engine 10 similar to that of FIGS. 1 .and 2 is rigidlysuspended from a transparent dome 46 by a strut 48. The dome is ratherstreamlined and serves to reduce the dynamic drag of the diver and hisequipment. Several equalizing ports 50 near the bow of the dome and apair of arm straps 52 may be .attached to the lower inner surface of thedome.

As in the first embodiment, the engine is powered by compressed air fromthe divers breathing tank through a line 52 passing through the dome andthe strut 48 into the engine duct at the point of maximum staticpressure. The valve 34 controls the flow of air to the line 32' andconveniently may be provided with a remote control flexible cable 56extending forwardly to the bow of the dome where it may be readilymanipulated by the diver. It will be obvious that an-exhalation line,similar to that of FIGS. 1 and 2, may be provided in the FIG. 5 deviceto utilize the divers exhaust breath.

Those skilled in the art will readily appreciate that numerousmodifications of the illustrated embodiments may be madewithoutdeparting from the spirit of my invention, therefore it is notintended that the scope of my invention be limited to those embodimentsillustrated and described but, that its breadth be determined by theappended claims and their equivalents.

Having thus described my invention, what I claim is new and desire toobtain by Letters Patent of the United States is:

1. An underwater propulsion apparatus for skin divers, comprising atubular engine having an elongated body provided with a forwardlypositioned inlet and a rearwardly positioned outlet of generally equalsize, a passage in the body of said engine and connecting with saidinlet and said outlet, the mid-portion of said passage being larger incross section thansaid inlet and said outlet, the widest portion of saidpassage constituting a duct station corresponding to the maximum staticwater pressure within the duct when said engine is propelled forwardlyunder water pressure within the duct, conduit means for injecting airinto said engine at said duct station, means for mounting said engine ona diver, underwater breathing apparatus including a portable tank ofcompressed .air adapted to be secured to a diver, a conduit from saidtank to said duct station, and means for controlling the flow of air tosaid station.

2. An underwater propulsion device in combination with an underwaterbreathing apparatus for skin divers, comprising a tubular engine housinghaving a fluid passageway extending from one endthereof to the other,said passageway being greater in cross-sectional area at its mid-portionthan at the inlet and outlet thereof, an air injection station locatedat the widest portion of said passageway, a compressed air tankassociated with said underwater breathing apparatus, a conduitconnecting said station with said air tank, and control means forregulating the flow of air to said station from said tank.

3. An underwater propulsion device according to claim 2 wherein saidengine is provided with a conduit connecting said station to the diversmouth to direct the divers exhaled air to said station.

4. An underwater propulsion devcie according to claim 2, in which saidcontrol means comprises a valve having an elongated flexible controlstem, and an adjustment handle drivingly connected with said stem andadapted to be mounted in an accessible position upon a diving harnessfor manual adjustment by a diver.

5. A combination underwater breathing and propulsion device for skindivers, comprising a compressed air tank, a tubular engine housinghaving an inlet, an outlet, and a fluid passageway extendingtherebetween, means mounting said housing on said tank, said passagewayhaving a greater cross-sectional area at its mid-portion than at theinlet and outlet thereof, a branched conduit including a breathing tubeportion for supplying air to a diver and a conduit connected to themid-portion of said passageway, and control means for independentlyregulating the flows of air to said breathing tube and to saidpassageway from said tank.

Varney Oct. {24, 1950 Goodman Dec. 7, 1954

